首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2732篇
  免费   160篇
  国内免费   16篇
耳鼻咽喉   15篇
儿科学   89篇
妇产科学   87篇
基础医学   314篇
口腔科学   49篇
临床医学   284篇
内科学   594篇
皮肤病学   28篇
神经病学   179篇
特种医学   170篇
外科学   335篇
综合类   44篇
一般理论   1篇
预防医学   218篇
眼科学   69篇
药学   193篇
中国医学   3篇
肿瘤学   236篇
  2022年   21篇
  2021年   48篇
  2020年   24篇
  2019年   21篇
  2018年   43篇
  2017年   29篇
  2016年   44篇
  2015年   45篇
  2014年   78篇
  2013年   88篇
  2012年   145篇
  2011年   131篇
  2010年   86篇
  2009年   85篇
  2008年   122篇
  2007年   110篇
  2006年   106篇
  2005年   94篇
  2004年   93篇
  2003年   84篇
  2002年   78篇
  2001年   68篇
  2000年   68篇
  1999年   67篇
  1998年   43篇
  1997年   45篇
  1996年   38篇
  1995年   38篇
  1994年   25篇
  1992年   48篇
  1991年   56篇
  1990年   42篇
  1989年   48篇
  1988年   58篇
  1987年   53篇
  1986年   54篇
  1985年   56篇
  1984年   29篇
  1983年   30篇
  1980年   21篇
  1979年   40篇
  1978年   32篇
  1977年   23篇
  1975年   22篇
  1974年   27篇
  1973年   34篇
  1971年   30篇
  1970年   20篇
  1968年   22篇
  1966年   21篇
排序方式: 共有2908条查询结果,搜索用时 15 毫秒
1.
For 50 years now, sacrospinous ligament fixation (SSLF) has been used to treat pelvic organ prolapse consequent on altered integrity of the pelvic myofascial structures. It is usually performed vaginally, but it has recently been performed laparoscopically through either an anterior or a posterior approach, with the broad ligament as a landmark to differentiate the two. In the present study, these two laparoscopic approaches were assessed using Thiel-embalmed cadavers. The anterior and posterior approaches were compared in terms of the closest distance to anatomical structures at risk, including pelvic viscera, the obturator nerve, and vascular structures. The posterior approach was more often closer to the investigated vessels and the rectum. The obturator nerve and the ureter were close to both the anterior and posterior approaches. The urinary bladder was closer using the anterior approach. From an anatomical standpoint, therefore, the anterior laparoscopic approach for SSLF is more likely to cause injury to the urinary bladder, whereas the posterior approach is more prone to causing rectal and vessel injuries. This study illustrates, from a basic science perspective, the importance of combining fascia research, novel endoscopic or minimally invasive surgical exposures informed by anatomy, and contemporary trends in gynecology in order to improve patient outcomes. Clin. Anat. 33:522–529, 2020. © 2019 Wiley Periodicals, Inc.  相似文献   
2.
BACKGROUND: There are limited studies of large cohorts of patients with specific polysaccharide antibody deficiency (SPAD) syndrome. OBJECTIVE: To study the clinical and laboratory characteristics of patients with specific polysaccharide antibody deficiency syndrome. METHODS: We retrospectively studied 75 patients with total IgG levels of at least 500 mg/dL and fewer than 9 of 12 responses to vaccination with pneumococcal vaccine polyvalent. Exclusion criteria included an IgG level less than 500 mg/dL, established immunodeficiency syndrome, and secondary immunodeficiency. RESULTS: The most common clinical presentation was frequent infections (n = 69; 92%), including sinusitis (n = 53; 77%), pneumonia (n = 29; 42%), ear infections (n = 18; 26%), and bronchitis (n = 19; 28%). Other presentations were systemic infections (n = 5; 7%), autoimmune or rheumatic diseases (n = 6; 8%), and chronic diarrhea (n = 4; 5%). The median IgG2 level of patients with no response to pneumococcal vaccine polyvalent tended to be lower than that of patients with at least 1 response (150 vs 193 mg/dL, respectively; P = .06). There was no association between total IgG level (categorized as 500-600 or > or = 600 mg/dL) and frequency of infection (P = .43). Patients with fewer responses to pneumococcal vaccine polyvalent and a higher frequency of infections were more likely to receive intravenous immunoglobulin (IVIG) therapy (P = .01 and .003, respectively). Treatment with IVIG significantly reduced the number of infections (P < .001). CONCLUSION: Patients with no response to pneumococcal vaccine polyvalent tended to have lower IgG2 levels; those with fewer responses were more likely to receive IVIG therapy.  相似文献   
3.
Zusammenfassung In Versuchen am Herzspitzen- und Herzstreifenpräparat und am ganzen herausgeschnittenen Herzen des Frosches wird bewiesen, daß für den Anstieg der einphasischen Aktionsspannungskurve nicht nur die Entwicklung des Aktionspotentials im einzelnen Herzmuskelelement maßgebend ist, sondern auch die Errguungsleitung.Mit 4 Abbildungen.Ausgeführt mit Mitteln der W. G. Kerckhoff-Stiftung 1938/39. Abgeschlossen am 1. September 1939.  相似文献   
4.
硫酸多糖对体外人脐静脉内皮细胞损伤的保护作用   总被引:8,自引:1,他引:7  
研究表明,硫酸多糖体外对多聚阳离子和氧自由基损伤的人脐静脉内皮细胞有保护作用。肝素、硫酸软骨素A抗多聚阳离子损伤作用比同浓度低分子肝素和甘糖酯强。肝素、硫酸软骨素A、甘糖酯抗氧自由基损伤作用优于同浓度低分子肝素。结果显示硫酸多糖有保护血管内皮的作用,其作用可能与所带阴离子基团有关。  相似文献   
5.
6.
The Bohr effect describes the usually negative coupling between the binding of oxygen and the binding of protons to respiratory proteins. It was first described for hemoglobin and provides for an optimal oxygen supply of the organism under changing physiological conditions. Our measurements of both oxygen and proton binding to the 24-meric tarantula hemocyanin establish the unusual case where a respiratory protein binds protons at low degrees of oxygenation but releases protons at high degrees of oxygenation. In contrast to what is observed with hemoglobin and other respiratory proteins, this phenomenon amounts to the inversion of the Bohr effect in the course of an oxygen-binding curve at a given pH value. Therefore, protons in spider blood can act either as allosteric activators or as allosteric inhibitors of oxygen binding, depending on the degree of oxygenation of hemocyanin. These functional properties of tarantula hemocyanin, which cannot be explained by classical allosteric models, require at least four different conformational states of the subunits. Inspection of the known x-ray structures of closely related hemocyanins suggests that salt bridges between completely conserved histidine and glutamate residues located at particular intersubunit interfaces are responsible for the observed phenomena.  相似文献   
7.
Two new dipeptidyl nikkomycins of the Z and X type were isolated from the culture broth of Streptomyces tendae TU 901/395-11/32 and characterized. They show a variation in the amino acid moiety of the molecule. Nikkomycin Wz is composed of L-tyrosine and 5-amino-5-deoxy-D-allo-furanuronic acid N-glycosidally bound to uracil, whereas nikkomycin Wx is composed of L-tyrosine and 5-amino-5-deoxy-D-allo-furanuronic acid N-glycosidally bound to 4-formyl-4-imidazolin-2-one. The new nikkomycins are good inhibitors of chitin synthetase from Coprinus cinereus but they did not inhibit growth of fungi and yeasts.  相似文献   
8.
9.
In seven patients (mean age 22 years) with injuries of the pelvic ring, the rupture of the symphysis was treated by polydioxanone ligaments. Complete rupture of the ileosacral joint was treated twice by additional external fixation, twice a compression screw osteosynthesis was applied. Incomplete iliosacral rupture in another three cases was not operated. Patients were treated functionally without signs of loosening or instability. After a control examination after 5 months all patients were free of symptoms in the area of the symphysis. Infection of the operation area did not accur. In our opinion the advantages of this method are simple operative technique, reduced risk of infection and no need for removal of metallic implants. Our excellent initial experience with synthetic PDS ligaments in operative treatment of symphysis ruptur seem to justify its application for other injuries like iliosacral or acromioclavicular rupture.  相似文献   
10.
Administration of either the muscarinic antagonist scopolamine or the benzodiazepine diazepam prior to training produced a dose-dependent impairment in the retention of one-trial inhibitory avoidance training in mice. To investigate the nature of this drug effect, the effects of scopolamine and diazepam were subsequently assessed on both acquisition and retention of inhibitory avoidance using a multiple-trial, training-to-criterion procedure. The training was conducted using either continuous trials in which the mouse was free to shuttle back and forth between shock and safe compartments or discrete trials in which the mouse was moved from the shock compartment of the safe compartment at the start of each trial. In either case, training continued until the mouse refrained from crossing into the shock compartment for a specified length of time on a single trial. Scopolamine (1.0 mg/kg) administered before training significantly increased the number of trials required to attain criterion, but did not affect retention when these mice were tested 2, 16, or 28 days later. In contrast, diazepam (1.0 mg/kg) did not significantly alter the number of trials necessary to reach criterion, but impaired retention of the inhibitory response in mice trained using discrete trials. The differences in the amnestic effects of scopolamine and diazepam revealed by this detailed analysis suggest that diazepam does not impair inhibitory avoidance performance through an effect on cholinergic function.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号